1. Field of the Invention
The present invention relates to a bar clamp and more particularly to a quick-action bar clamp with a non-round slide bar with multiple teeth and a pawl assembly to engage with teeth. A movable jaw can be rapidly advanced and released easily when a workpiece is clamped between a movable and a stationary jaw.
2. Description of Related Art
A bar clamp operated with one hand is used to clamp two articles together and is more convenient than a bar clamp that requires two hands to operate. With reference to FIG. 8, a conventional bar clamp comprises a slide bar (70), a stationary jaw (71), a movable jaw (72), a body (73), a drive assembly and a brake (76). The movable jaw (72) opposes the stationary jaw (71) and is mounted at one end of the slide bar (70) that is movably mounted through the body (73). The slide bar (70) has a top edge and a bottom edge.
The body (73) has a top, a bottom, a front edge, a cavity (731), a transverse hole (732) and a handle (74). The stationary jaw (71) is formed on the top of the body (73). The cavity (731) is defined in the body (73) and the slide bar (70) passes through the cavity (731). The transverse hole (732) is formed in the front edge of the body above the slide bar (70). The handle (74) is formed at the bottom of the body (73).
The drive assembly comprises a trigger (75), a drive lever (751) and a spring (752). The trigger (75) has a top, a bottom, a front edge and rear edge and is pivotally mounted in the body (73) corresponding to the handle (74) so the top of the trigger (75) is in the cavity (731). The drive lever (751) has a front surface, a rear surface and a hole (not numbered) through which the slide bar (70) passes, is suspended on the slide bar (70) and abuts the rear edge of the trigger (75). The hole of drive lever (751) has a top edge and a bottom edge. The spring (752) has two ends and is mounted around the slide bar (70) in the cavity (731). One end of the spring (752) abuts the drive lever (751), and the other end abuts an interior surface of the cavity (731).
The brake (76) has a central hole and is pivotally attached to the transverse hole (732) in the front edge of the body (73). The slide bar (70) passes through the central hole in the brake (76). The central hole in the brake (76) has a top edge and a bottom edge. A compression spring (762) is mounted between the brake (76) and the front edge of the body (73) so the brake (76) is pushed to an inclined standby position.
To move the movable jaw (72) toward the stationary jaw (71), the trigger (75) is squeezed toward the handle (74), and the trigger (75) pivots the drive lever (751). The hole in the drive lever (751) is inclined so the top and bottom edge of the hole grip the top and bottom edges of the slide bar (70) and push the slide bar (70) back. As the drive lever (751) pushes the slide bar (70) back, the movable jaw (72) moves toward the stationary jaw (71). The slide bar (70) is kept from moving forward by the brake (76) because the central hole in the brake (76) grips the top edge and bottom edge of the slide bar (70) when the trigger (75) is released. The compression spring (762) keeps the brake (76) in position to grip the slide bar (70) to prevent the slide bar (70) from moving forward.
However, the conventional bar clamp has some shortcomings that include:
1. Bad engagement effect:
Because the drive lever (751) and the brake (76) must be inclined to grip the slide bar (70) and the top and bottom edges of the slide bar (70) are flat and smooth, the drive lever (751) and the brake (76) occasionally slip. When the movable jaw (72) and the stationary jaw (71) clamp a workpiece with a lot of force, the force acting on the movable jaw (72) will cause the movable jaw (72) to move away from the stationary jaw (71) unless the brake (76) engages the top and bottom edges of the slide bar (70).
2. Disengaging the brake (76) from the slide bar (70) is not easy:
Because the brake (76) applies a transverse force to the edge of the slide bar (70), the pressure of the brake (76) acting on the slide bar (70) is unstable. When the brake (76) does securely hold the slide bar (70) in position, disengaging the brake (76) from the slide bar (70) is often difficult.
3. The slide bar (70) is not durable:
The drive lever (751) and the brake (76) engaging the edge of the slide bar (70) and will damage the edge. After extensive use, the slide bar (70) will not hold the moveable jaw (72) in all positions and will have to be replaced.
To overcome the shortcomings, the present invention provides an improved bar clamp to obviate or mitigate the aforementioned problems.
A quick-action bar clamp in accordance with the present invention includes a non-round slide bar with a series teeth is movable mounted in a body. Clamp means includes a stationary jaw mounted at a top of the body and a movable opposing the stationary jaw is connected to one end of the slide bar. A drive assembly includes a handle formed at a bottom of the body and a trigger opposing the handle pivotally mounted in the body to advance the slide bar by squeezing the trigger toward the handle. A pawl assembly includes a pawl engages with the teeth of the slide bar to prevent a reverse motion of the slide bar when the trigger is released.
Accordingly, an objective of the invention is to provide an improved quick-action bar clamp that provides a nice clamping purpose.
Another objective of the invention is to provide a quick-action bar clamp to release the movable jaw easily when a workpiece is clamped.
Still another objective of the invention is to provide a quick-action bar clamp wherein the bar clamp is one-hand operable.
Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.